Performance Evaluation of Fiber Reinforced Hot Mix Asphalt Containing Reclaimed Asphalt Shingles

Reclaimed asphalt shingles (RAS) offer a promising avenue for increasing recycled content in hot mix asphalt, but the aged, stiff binder they contribute tends to reduce cracking resistance, particularly at intermediate temperatures. This study investigated whether polymer fiber reinforcement can offset that brittleness while preserving rutting and moisture performance in mixtures containing both reclaimed asphalt pavement (RAP) and RAS. Fourteen asphalt mixtures were designed using a base blend of 25% RAP combined with RAS at either 3% or 5% by total mix weight. Two commercially available polymer fiber types, designated Fiber A and Fiber B, were added at dosages of 0.05%, 0.10%, and 0.15% by total weight. All mixtures were evaluated for rutting resistance and moisture susceptibility using the Hamburg Wheel Tracking test and for intermediate-temperature cracking resistance using the IDEAL Cracking Test. Statistical comparisons were carried out using one-way ANOVA with Tukey adjusted pairwise contrasts against the control mix. Fiber addition did not compromise rutting performance and, in several cases, produced statistically significant reductions in rut depth. All mixtures satisfied the Hamburg moisture damage threshold. Cracking resistance improved substantially with fiber reinforcement, with Fiber B consistently outperforming Fiber A across both RAS levels. Statistically significant improvements in CTindex were observed most reliably at the 0.10% and 0.15% dosages of Fiber B. These results indicate that polymer fiber reinforcement can support higher recycled material usage in asphalt mixtures without sacrificing mechanical performance, offering a practical path toward more sustainable pavement design within a balanced mix design framework.